Re: Stewart Warner "Yenko Tach"
 

According to the original Stewart Warner installation instructions for the monitor: 990-A = Transistor ignition, 990-B= std. battary ignition, 990-D = Magneto ignition, there is no 990-C listed.

Re: Stewart Warner "Yenko Tach"
 

The 977-M is the panel mount the 977-J is pedistal with black face and a different sweep than the more popular 970 model. 970-C is a 10K Pedestal mount custom face. 970-B is the same only 8K. 970-K =10k black face pedestal mount. 970-J =8K black face Pedestal mount. 970-F =10k Custom panel mount. 970-E = 8k Custom panel mount. 970-N =10k Black face panel mount. 970-M =8K Black face panel mount. This is right from the 1970 catalog. The 990-D ignition monitor is adjustable and can be used with point ignition. Still confused? Just in case you wondered, price for a 990-B monitor: $4.03 990-D $8.05. Tach's, your choice 977 or 970 pedistal mount $52.25. I'll take a case of each please!
BKH